Remove gala-daemon

[leolost2605]

I'm not 100% sure whether this is correct but since gala daemon is now started by gala I don't think it belongs in the required components in session settings?

[bobby285271]

This PR is actually necessary for me to start Pantheon on NixOS after elementary/gala@351722c, otherwise gnome-session complains gnome-session-binary[1377]: WARNING: Unable to find required component 'gala-daemon'

It sounds like in gnome-session handle_required_components reads the key file, iterates RequiredComponents and invokes gsm_util_find_desktop_file_for_app_name to search the desktop files in gsm_util_get_desktop_dirs (including autostart dirs and applications dirs). So when elementary/gala@351722c removes the desktop file it makes sense to me to experience startup issues.

Though this PR also replaces gala-wayland with gala in pantheon-wayland.session's RequiredComponents, I didn't actually test the wayland session and it is unclear for me why this is needed...

[leolost2605]

Though this PR also replaces gala-wayland with gala in pantheon-wayland.session's RequiredComponents, I didn't actually test the wayland session and it is unclear for me why this is needed...

Tbh I'm not sure why I did this either so I reverted it😅